In this research methanolic extracts of three Phlomis species, (P. aucheri L., P. caucasica L. and P. lanceolata L.) were examined for their antioxidant properties. Two biochemical assays, namely 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and metal-chelating activity, systems were used to evaluate antioxidant activity. Total phenol and flavonoid contents of the species were determined by Folin-Ciocalteu and AlCl3 assays, respectively. The essential oils were obtained by water-distillation using a Clevengertype apparatus and analyzed by GC-MS method. Results indicated that the extracts are not significantly different (P< 0.05) in total phenol content. Results from antioxidant activity assays showed that the extracts are more active in DPPH radical scavenging assay, but lower active in metal-chelating assay than ascorbic acid as a synthetic antioxidant. In addition, results from GC-MS analysis showed that the essential oil of P. aucheri was characterized with cyclopentane (77.2 %) as major constituent, cyclopentane (35.4 %) and germacrene-D (28.2 %) as major components in the essential oil of P. caucasica, and octacosane (50.9 %) described as major component in the essential oil of P. lanceolata. All extracts represented strong antioxidant activity and suggest their potential to apply as antioxidant agents.
